Endometrosis in more advanced stages can cause complications in births aided by infertility treatments. Specifically, the chances for preterm birth and placenta previa were significantly increased in these women, according to researchers at the University of Tokyo.
The study, “Assisted reproductive technology pregnancy complications are significantly associated with endometriosis severity before conception: a retrospective cohort study,” was published in the journal Reproductive Biology and Endocrinology.
Previous studies have linked endometriosis to pregnancy complications in the second to third trimester, such as preterm birth and placenta previa, a complication in which the placenta is unusually low in the uterus, possibly blocking it and interfering with a normal delivery. Some researchers have, however, expressed doubts about the data supporting this link.
The authors did a retrospective cohort study to investigate whether endometriosis severity is associated with the incidence rates of adverse pregnancy outcomes.
Their analysis included 631 deliveries of babies, born to mothers who used assisted reproductive technology, like artificial insemination performed at their hospital between March 2000 and December 2014. Participants included 92 women with surgically diagnosed endometriosis, and 512 without endometriosis.
In the endometriosis group, 10 women were classified as revised American Society for Reproductive Medicine (rASRM) stage 1 and 2, 31 were rASRM stage 3, and 43 were rASRM stage 4 (in the other 8 cases, there was no record of an rASRM stage).
Researchers indeed found that women with endometriosis showed higher frequencies of pregnancy complications, specifically preterm birth and placenta previa. Another complication, the frequency of small for gestational age, was not seen in this group.
Looking specifically at the stage of disease according to rASRM, they found the frequencies of preterm birth and placenta previa were significantly increased in women with rASRM stage 4 endometriosis, relative to those with rASRM stage 1-3 and women without endometriosis. No significant differences were found in a comparison of women with less severe endometriosis (rASRM stages 1 through 3).
These results show that women with advanced endometriosis appear to have higher preterm births and incidents of placenta previa, compared to women in earlier stages. Moreover, since the analyzed pregnancies were performed with assisted reproductive technology, these results also suggest that their pregnancies are more complicated, a relevant fact for obstetricians when identifying potential high- and low-risk pregnancies.